In this age of increased air pollution, the removal of chemicals from the air we breathe is a concern of everyone. In addition, in the fabrication electronic materials and of devices such as semiconductors, there is a requirement for uncontaminated air of high quality.
Gas phase filtration is commonly accomplished using activated carbon manufactured in various ways. One approach uses a carbon/adhesive slurry to glue the carbon to the substrate. The adhesive decreases carbon performance by forming a film on its surface.
A second approach involves carbonizing an organic based web by heating, followed by carbon activation. This material is expensive and has relatively low adsorption capacity.
A third approach involves forming a slurry of carbon powders and fibers into sheets by a process analogous to a wet papermaking process. This material has a medium-to-high cost, and has an undesirable high pressure drop. Moreover, chemically impregnated carbon particles cannot be efficiently used in conjunction with an aqueous process, as the aqueous nature of the process either washes away the chemical used to impregnate the carbon, or reacts undesirably with the impregnating or active chemical groups thereby rendering it inoperative. In general, however, filter materials which do not incorporate chemically active groups perform far less effectively than those which do include chemically active groups.
None of these approaches fully achieve the desired properties which provide a clean, cost effective, high efficiency, low pressure drop, adsorptive composite.